Yard broke Commons rules over search of MP's office Commons

Home Office officials believe the police broke the rules because they failed to tell Serjeant at Arms Jill Pay that she could simply have refused permission.

The finding is a setback for assistant commissioner Bob Quick, the head of the Yard investigation into Whitehall leaks and a contender for the job of Metropolitan Police Commissioner.

Home Secretary Jacqui Smith ordered officials to get to the bottom of the matter after Speaker Michael Martin used his dramatic statement to the Commons yesterday to criticise the police.

In response, Mr Quick is understood to have written a letter to Ms Smith that says his officers did not make it clear to the Serjeant that consent was optional. The Home Secretary is likely to refer to his letter when she makes a statement to the Commons today and may even publish it.

A source said: "The letter is not explicit but our reading of it is that the Speaker was correct in his statement. It is not disastrous for the police but it is certainly unfortunate if they cannot show they followed procedure to the letter in such a high-profile case."

The Speaker sharply criticised the police yesterday, saying that permission to search the Commons should not have been given. "I have been told that the police did not explain, as they are required to do, that the Serjeant was not obliged to consent or that a warrant could have been insisted on," he told MPs. Officers took away computer equipment containing confidential files from Mr Green's office. The Speaker has demanded that the equipment be returned to the MP before Monday.

Police sources admit that technically they failed to inform officials of their right to refuse the search and should have done so.

But they also say that they were told that Ms Pay was taking legal advice about the search. The source said : "She did seek legal advice and one would have hoped that the advice would have come back and told them of their right to refuse the search."

Scotland Yard insists its search of Mr Green's Commons office was lawful. Officers say that under the Police and Criminal Evidence Act they do not need a warrant to search a premises if the person responsible gives their consent.

There has been controversy over whether the person responsible for MPs' offices is the Speaker or the Serjeant at Arms. Officers say they sought permission from Ms Pay because she is directly responsible for the protection and security of the House of Commons.

There is also the issue of whether the Serjeant at Arms should have informed the speaker but police say that it is a matter for Commons officials.

Mr Martin revealed yesterday that the Serjeant signed a consent form for the search Thursday without consulting him or the Clerk of the Commons Malcolm Jack. He said a warrant and the express permission of the Speaker would be required for future searches.

John Silverman, professor of criminal justice at Bedfordshire University, insisted that the raid broke the law.